Unless otherwise indicated herein, the materials described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section.
A radio access network (RAN) may include a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. Further, each base station may include or be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the Internet and/or the public switched telephone network (PSTN) for instance. With this arrangement, a UE within coverage of the RAN may engage in air interface communication with a base station and may thereby communicate via the base station with various entities on a transport network and/or with other UEs served by the RAN.
In general, the network infrastructure in such a RAN may include a switch or gateway system that physically connects with one or more transport networks. Further, the network infrastructure may include a controller, integrated with or separate from the switch or gateway system, that manages various RAN functions such as registration and tracking of UEs in the RAN and setup and control of bearer connections for UEs.
For instance, when a UE begins operating in coverage of the RAN, the controller may receive from the UE a registration or “attach” request, and the controller may responsively trigger authentication of the UE and obtain and store a service profile record for the UE. In turn, as the UE moves throughout the RAN, the controller may receive tracking area updates from the UE and may process those updates to record where in the RAN the UE is located, so as to facilitate paging the UE or the like.
Further, when a UE is served by a particular base station, the controller may engage in signaling with the base station and with the switch or gateway system to set up one or more bearer connections for carrying communication traffic between the UE and the switch or gateway system, and thus between the UE and one or more transport networks. And the controller may manage each such bearer connection, including maintaining context data for the bearer connection, engaging in signaling to suspend, resume, release, or transfer the connection between base stations, and so forth.
In addition, such a controller in one RAN may have a signaling interface with another RAN, through which to engage in signaling to facilitate transition of a UE to be served with communications by the other RAN. For instance, a first RAN may primarily serve UEs with packet-data communication service, a second RAN may primarily serve UEs with PSTN voice call communication service, and the first RAN may include a controller that has a signaling interface for engaging in signaling with the second RAN. In a “circuit-switched fallback” (CSFB) arrangement, when a UE is being served by the first RAN and the UE seeks to place a PSTN voice call, or the second RAN seeks to connect a PSTN voice call to the UE, the second RAN may engage in call setup signaling with the UE through the controller of the first RAN.
For instance, the UE may transmit via its serving base station to the controller a PSTN voice call origination request, and the controller may send that request to an interworking server (IWS) of the second RAN, which may pass the request to a controller of the second RAN. The controller of the second RAN may then work to set up the requested PSTN voice call, and may engage in further signaling with the UE via the controller of the first RAN. Alternatively, a controller of the second RAN may transmit to the UE via the controller of the first RAN a page message to alert the UE of an incoming PSTN voice call. In either case, as a result of the inter-RAN signaling, the UE may then ultimately transition from being served by the first RAN to being served by the second RAN so as to engage in the PSTN voice call served by the second RAN.
When a UE engages in such a transition, the controller of the first RAN, as manager of bearer connections for the UE in the first RAN, may suspend one or more bearer connections that were in place for the UE in the first RAN, pending return of the UE to be served by the first RAN. Upon completion of the PSTN voice call, the UE may then return to be served by the first RAN, and the controller of the first RAN may resume the suspended bearer connection(s), to enable the UE to engage in further packet-data communication served by the first RAN.